LTC4449 datasheet(53/108 Pages) LINER

53 / 108 page

LTC3882-1

Rev A

For more information www.analog.com

38821 F34

100ms/DIV

VOUT2

VOUT3

VOUT4

VOUT1

1V/DIV

APPLICATIONS INFORMATION

Figure 34. LTC3882-1 Time-Based Ratiometric Ramping

Figure 35. Cascade Sequencing Configuration

LTC3882-1

PGOOD0

PGOOD1

RUN 1

RUN 0

START

LTC3882-1

38821 F35

RUN 0

PGOOD0

PGOOD1

TO NEXT CHANNEL

IN THE SEQUENCE

(PGOOD PULL-UP RESISTORS

TO 3.3V NOT SHOWN)

RUN 1

Figure 31. Example of 1ms TON_RISE

Figure 33. LTC3882-1 Time-Based Coincident Supply Ramping

Figure 32. LTC3882-1 Time-Based Supply Sequencing

Figure 35. This configuration hardware disables the next

downstream controller anytime the output is not within

the specified UV and OV limits, or the upstream controller

is disabled. When indicating power is not good, there is

a 30µs deglitching filter on the PGOOD output to assure

the signal does not toggle repeatedly at lower values of

TON_RISE/FALL due to noise on VOUT. If unwanted transi-

tions still occur on PGOOD due to noise or longer rise/fall

settings, place a capacitor to ground on the PGOOD pin

to further filter the waveform. The RC time-constant of

the filter should be low enough to assure no appreciable

delay is incurred. A value of 300μs to 500μs will provide

some additional filtering without significantly delaying

the trigger event.

38821 F31

VOUT

(1V/DIV)

RUN

(5V/DIV)

200µs/DIV

38821 F32

VOUT2

VOUT3

VOUT4

VOUT1

100ms/DIV

1V/DIV

38821 F33

100ms/DIV

VOUT2

VOUT3

VOUT4

VOUT1

1V/DIV

38821 F36

100ms/DIV

VOUT2

VOUT3

VOUT4

VOUT1

1V/DIV

Figure 36. Cascade Sequencing Waveforms

When the system is turned off, rails will shut down in the

same order as they turn on, as shown in Figure 36. If a

different sequence is required, the circuit must be rewired

or delays must be added by programming TON_DELAY or

TOFF_DELAY.Afundamentallimitationofthisapplicationis

the inability of upstream rails to detect a start-up failure of

LTC4449 Datasheet(PDF) 53 Page - Linear Technology

LTC4449 Datasheet(HTML) 53 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL